Fibrous material, e.g. synthetic fibers and natural fibers, are sold and delivered to customers in compressed bales.
Different methods are employed to produce high-density fiber bales. In general, a fibrous material is pressed into a bale, and covered with a protective wrapping. However, the conventional methods fail to produce a high-density fiber bale substantially free of disrupting curvatures on a top side or a bottom side. Disrupting curvature on either the top side or the bottom side is problematic because it interferes with the storage of high-density fiber bales on top of each other, and it promotes debating complications, for example in acetate tow bales.
U.S. Pat. No. 3,991,670 discloses a pressing apparatus for compressing a mass of fibrous material, such as cellulose pulp, into a bale and wrapping the resulting bale with a wire or strap. There is used a bale press stand, a stationary first press plate movable toward, and away from said press plate, together with means for moving said second press plate. The second press plate has a pressure-applying face constituted by a planar border surface normal to the direction of movement of said second press plate and a centrally disposed portion projecting 10-50 mm from the plane of said border surface, for effecting a permanent depression, centrally in an end surface of a bale formed in said apparatus, facilitating the gripping and lifting of a wire or strap which is wrapped around a number of such bales.
U.S. Pat. No. 4,577,752 discloses an improved high density tow bale wrapped with cardboard or the like covering and held in compressed condition by multiple strappings which extend around the bale, the tow bale having on its bottom a pattern of multiple pads for supporting the bale on a floor and unrelieved areas between the pads for receiving the strappings therealong.
U.S. Pat. No. 5,852,969 discloses a bale press for compressing material such as cotton. The press includes a base frame structure and a pair of platens, which have generally rectangular bale compressing faces for compressing a cotton bale to facilitate the bale tying operation. A plurality of elongated, wedged-shaped, bale compression members are provided at least on one of the platens. These bale compression members protrude outwardly from the platen where they are mounted to provide a compression area, which is sufficiently small so that the cotton bale is compressed only in close proximity to the positions where a single bale tie is to be placed. A sufficient number of bale compression members are provided to facilitate the application of the ties required for the bale.
German Utility Patent No. DE 296 15 598 U1 discloses the use of a conical shape compression shield and ejector to facilitate not only the compression of the materials downwardly, but also in the direction toward the side walls of the press.
International Publication No. WO 03/089309 discloses a highly compressed cuboid-shaped filter tow bale having a top side and a bottom side free from noisome curvatures and constrictions. This bale is entirely wrapped with a mechanically self-supporting, elastic packing material, which is provided with one or several convectively airtight connections. The method for producing the highly compressed cuboid-shaped filter tow bale includes the following steps: a) filter tow is supplied in a compressed form; b) the compressed filter tow is enveloped in a wrapping; c) the wrapping is closed in an airtight manner; and d) the wrapped bale is relieved of the load (e.g., by application of vacuum).
Despite the research efforts in developing high-density fiber bales suitable for storage and delivery, there is a still a need for a fiber bale, which is relatively easy to manufacture at a low cost. Furthermore, there is still a need for a method of producing high-density fiber bales suitable for storage and delivery, which requires the least amount of modifications of the current techniques and equipments, e.g. press, employed in producing high-density fiber bales.